Effect of ZnO:Al Thickness on the Open Circuit Voltage of Organic/a-Si:H Based Hybrid Solar Cells

Hybrid solar cells are based on the concept of using both organic and inorganic materials for fabrication of devices. Hybrid solar cells, based on a heterojunction between inorganic electron acceptor layer and organic donor layer, has been fabricated. Effect of electron transport layer on open circuit voltage (Voc) of hybrid solar cells was investigated. Hybrid solar cells were fabricated using amorphous silicon as main absorbing layer and as electron acceptor layer while using copper phthalocyanine (CuPc) as the donor materials. Al doped ZnO layer was used as buffer layer between ITO and a-Si:H to prevent ITO from reacting with silane gas during plasma enhanced chemical deposition (PECVD) process. ZnO:Al thin film also acts as electron transport layer. The open circuit voltage of hybrid solar cells studied with varying the thickness of ZnO:Al layer. Voc was increased from 0.30 volt to 0.52 volt with increasing the thickness of ZnO:Al layer from 15 nm to 45 nm. The poor interface between inorganic (a-Si:H) and organic layers may be a possible reason for low fill factor and low photocurrent in hybrid solar cells.